Radio receiver



June 19, 1945. i sTRlKER 2,378,663

' RADIO RECEIVER- Filed Jan. 16, 1942 Sheets-Sheet 1 RH! ION 4974575 EVEM5 1 BEID/ I I I annals Amman AND V zsumns cvuima l 9 umns ALL DAYISMETEB mums U 1 W DIAL .June 19, 1945. G. o. STRIKER Q RADIO RECEIVERFiled Jan. 16, 1942 5 Sheets-Sheet 2 2E wmm June 19, 1945. G. o. STRIKERRADIO RECEIVER Filed .Jan; 16; 1942' 5 Sheets-Sheet 3 IIIIIIIIIIAlll'llll 3 6 H. M w 7 2 m m X, d w 6%% 2 4 I I I I ll. mm L. Mm I I I I II R I 1 Tm :1 s n .m& s mm.

June 19, 1945.

Patented June 19, 1945 RADIO RECEIVER George 0. Striker, Chicago, 111.,assignor to Zenith Radio Corporation, Chicago, 111., a corporation ofIllinois Application January 16, 1942, Serial No. 426,991

43 Claims.

and other forms or interference.

A further object of the invention is to provide a radio receiver with a,short wave loop antenna which may be located at positions relativelyremote from the receiver.

A further object of the invention is to provide means for tuning theloop to adapt it for the reception of signals in different bands.

A further object of the invention is to provide a radio receiver with aplurality of antennae with means whereby the preparation of one antennafor use renders another antenna inoperative.

A further object of the invention is to provide a radio receiver havinga fish-pole antenna and switch means controlled thereby connecting anddisconnecting said antennato the input of the receiver and forconnecting and disconnecting another antenna from the input of thereceiver.

Other objects, advantages and capabilities of the invention will appearfrom the following description of a preferred embodiment thereof, takenin conjunction with the accompanying drawings, in which:

Figure l is a perspective view showing the manner in which the portableradio receiver may be used by a railroad passenger;

Fig. 2 is a front elevational view of the receiver, the front coverbeing opened;

Fig. 3 is a rear elevational view, the rear cover being removed to showinternal parts;

Fig. 4 is a sectional detail taken on the line 4-4 of Fig. 3 showing thetelescoped fish-pole antenna in cross-section and associated elements inelevation;

Fig. 5 is a front view of the mechanism shown in Fig. 4;

Fig. 6 is an elevational view of the two-loop antenna structure, a coverof the short wave loop being removed and an associated part thereofbeing shown in section;

Fig. 'I is a fragmentary plan view thereof on a somewhat larger scale;

Fig. 8 is a wiring diagram of the receiver;

Fig. 9 is a fragmentary rear view of the receiver with the rear coverremoved, showing a modified form of fish-pole antenna;

Fig. 10 is an elevational view partly in section of such fish-poleantenna in collapsed form; and

Fig. 11 is a view similar to the left-hand side of Fig. 6 showing amodified form of short wave antenna. 4

Referring to the drawings, the radio receiver as a whole is containedwithin a case 20 which is provided with ahinged front cover 2|. When thefront cover 2| is opened, music and other broadcast material may beemitted from the loud speaker 22.

Adjacent the loud speaker 22 is a panel 23 which serves as a mountingfor tone controls 24, a tuning control 25, and a volume control 26. Thetone controls 24 open and close the four switches 21 in Fig. 8 to effectcontrol of the tone. The tuning control 25 controls a gang of condensers28, 29 and 30 for tuning the RF input circuit, mixer input circuit, andoscillator circult, respectively (Fig. 8).

The volume control 26 controls the double-pole single-throw switch 3|(Fig. 8), and the volume control 82 also shown in that figure. Thetuning control actuates not only the gang of condensers but also thepointer 33 of the dial 34.

The dial 34 comprises indicia 35 corresponding to the broadcast band andfive sets of indicia 36 which correspond to five short wave bands, forexample, the 16-meter, the 19-meter, the 25- meter, the 31-meter, andthe 49-meter bands.

Adjacent the dial it is an escutcheon plate 31 which carries a series ofprojecting switch buttons 38, 39, 40, ll, 42 and 43, corresponding tothe broadcast bands just referred to.

As best seen in Fig. 2, the escutcheon plate 31 bears opposite thesebuttons the name of the corresponding band and also indicia adjacent thebuttons indicating when the best reception is received with that band.Thus, the best reception of the 49-meter band is in the evening, withthe 31- and 25-meter bands in the afternoon and evening, the l9-meterhand all day, and the IG-meter'band in the morning.

The double-pole single-throw switch 3| controls the supply of electricalenergy to the tubes of the receiver. This energy may be supplied by Aand B batteries 44 and 45 (Fig. 8) carried in the receiver case or itmay be supplied :by the plug 46 which may be inserted in any availablewall receptacle, the power pack associated therewith being arranged forA. C. and D. 0. operation. This power pack includes a rectifier tube 4.1and the filter instrumentalities illustrated in Fig. 8.

The receiver may be changed over from battery to power line operation bymeans of a fourpole double-throw switch 46 shown in power line positionin Fig. 8.

The band switch buttons 56 to 43 constitute the outer ends of axiallymovable switch bars bearing the same numbers and shown in Fig. 8. Inthis figure two views of each switch bar are shown in relativelyinverted relation. Thus, if one of the switch bars were actuated in Fig.8, then the upper showing of that bar would be displaced upwardly whilethe lower showing of that bar would be displaced downwardly.- The blackparts of the switch bars represent insulation and the white partsconducting material.

The bars 88 to 43 are associated with a looking bar 49 of known typeshown diagrammatically in Fig. 8. This locking bar is so arranged thatit holds any bar which is displaced inwardly in its inward switchingposition. The bar is so arranged that it is actuated to releasingposition by the inward movement of another bar. Consequently, only oneof the band switches 36 to 43 is operative at any time.

The receiver may suitably be a superheterodyne receiver, tube 50 being aradio frequency amplifier, tube 5|, the mixer, tube 52, an intermediatefrequency amplifier, tube 58, a detector and audio amplifier, tube 54, apower amplifier, and tube 55, the oscillator tube.

The receiver is provided with a, plurality of antenna structures whichwill now be described. For broadcast pickup, a loop antenna 58 of thetype described and claimed in Patents Nos. 2,164,- 251, 2,200,674,2,237,260, and 2,250,387, issued to Eugene F. McDonald, Jr., may beemployed.

The loop 56 is enclosed within a suitable nonconductive enclosure 51which is hinged to plate members 58. These plate members 58 carrysuction cups 59 whereby the loop may be mounted on the glass window 60of a conveyance. This conveyance may, for example, be a steel railroadcar, a bus, an airplane, or an automobile. Of course, the invention isnot intended to be limited to a conveyance since its antenna may be usedto great advantage in a steel or metallized house, or it may be usedirrespective of any enclosure whatsoever. Normally, the suction cups 59do provide a very simple quickly attachable and detachable means forsupporting the loop 56 on or near a dielectric wall such as a pane ofglass in an enclosure which is constituted for the most part by walls ofconducting material. It is within the scope of my invention to provideone or more suction cups to support loop 66.

The ends of loop 56 are connected to two leads 6| and 62, lead 62appearing in Fig. 8 as the outer conductor of a coaxial cable having acenter conductor 8|. For the purposes of the broadcast loop 56, it isimportant that the distributed capacity between the leads 6| and 62should be maintained low and should be maintained substantiallyconstant. For this reason the conductor 8! and its shield 62 are locatedalong one edge ofa stout ribbon 82 and the conductor 6| is located alongthe opposite edge of this ribbon. This ribbon is relatively broad andstill so that the spacing between the conductors at the opposite sidesis maintained substantially constant. The latter lead is connected to asmall loading coil 63 on a five-prong plug 6|. The five prongs are shownas ringed dots in the upper left-hand corner of Fig. 8. The conductor 6|is connected to one prong. The coil 63 is connected to another. A tap onthis coil is connected to still another prong.

On the receiver is mounted a three-position switch 65 which in oneposition shorts the upper part of the coil 63 and in another positionintroduces a small capacity 66 across the leads 6| and 62. In itsintermediate position the switch 65 has no eliect on the inductance orcapacity of the circuit including the loading coil 63 and the loop 56.The purpose of the switch 65 is to introduce a slight correction forimproving the tuning of the loop 56 which may be impaired by mountingthe loop too near the edge of a steel window, for example, or from someother cause. The capacity 66 may suitably be constituted by a few turnsof wire around the conductor leading to conductor 5| as is illustartedin Fig. 8.

The housing 51 also, contains a coil 80 of a few turns in closeproximity to the loop 56, the ends of the coil 60 being connected toterminals 9| and 92. In the case of a semi-permanent installation, forexample in the case of a sojourn at a country home, it may be desirableto operate with an outside aerial which may be connected to the terminalill, the terminal 92 being grounded. It will thus be seen that the coil90 is coupled to the loop 56 and that the operation for broadcastreception with an outside aerial is attained in a remarkably simplermanner.

For short wave reception the loop antenna 56 is no longer suitable. Anantenna having a low inductance and capacity is required. In accordancewith the present invention, I provide a short wave loop antenna 61 whichconsists essentially of a few turns of wire extending around a U- shapeddielectric tube 68. The tube 66 has its ends mounted in a housing 69which is hinged to the plates 58 as best seen in Fig. 6.

If the loop 61 were not tuned separately from the receiver and werelocated at a point remote from the receiver, the inductance andcapacitance of the connections between the loop and receiver, especiallyat high frequencies, would seriously mistune the loop. In fact, such aloop with its connections to the receiver would probably be resonant ata relatively low frequency. By providing a small degree of couplingbetween loop 61 and the receiver input circuit it is possible toeliminate the mistuning effect of the connections sufilciently that theloop 61 may be tuned substantially independently of the receiver even athigh frequencies. In accordance with this invention, adjustable tuningmeans is provided at the loop to tune the loop to any desired frequency.Such an arrangement is shown in Fig. 8. Opposite ends of the loop 61 areconnected across a condenser 10 which is arranged to tune the loop to adesired frequency within one of the short wave bands. A three-positionswitch H is arranged to cut in a condenser 12 or a condenser 13 intoparallel connection with the condenser 10 so as to tune the loop for twoother short wave bands of longer wave length.

When using a short wave loop such as loop 61 it is even more desirablethan with the broadcast loop 56 to provide a relatively longtransmission line for connecting the loop remotely to the receiver inputso that the loop may be placed in a position removed from the receiver.This is so because at high frequency the conductors of the receiveritself if too near the loop, shield or damp the loop even more so thanat lower frequencies and render it less effective to transmit a signalto the receiver input. At the same time, the use of such a line becomesmore dimcult at high frequencies because of radiation loss from andradiation pickup on the transmission line itself. Also, the problems ofshunt and stray capacity of the transmission line, discussed inconnection with the broadcast loop ll, become more troublesome. For thepurpose of transmitting signals intercepted by the short wave loop 91and transferring the same to the receiver located remotely from theantenna, and more specifically for transferring intercepted signals to acontrol grid of the mixer tube 6|, there is provided a link circuitextending in space from the loop 61 to the receiver and comprising afirst coupling coil 18 coupled to the loop 81. a Pair of conductors 62and 8|, a, switch Hi0, and three coupling coils l4, l and 16, allconnected in series relation. The coil 18 suitably comprises a singleturn of wire positioned closely to the loop antenna 61 and preferablyhas a common point therewith. The loop antenna 61 and the coil 19 thusform a step down transformer.

The switch Hill is closed when using the receiver with the short waveantenna 61 and is actuated by the flshpole antenna 93 as will beexplained hereinafter. The coils 14, I5 and 16 are located at thereceiver and coupled to coils 42a, Ma and 40a, respectively, which canbe connected in circuit with the tank circuit comprising the secondarywinding of transformer m and variable condenser 29 for the purpose ofapplying the signal intercepted by the antenna 61 to a control grid ofthe mixer tube 5|. The variable condenser 29 tunes the tuned circuit IM,29 to the same signal frequency as that to which the loop 81 is tuned.Tuning of the receiver input as well as the loop increases theselectivity of the set in an amount proportional to the product of thequality factors of the two tuned circuits. This is desirable for bestoperation of a superheterodyne receiver.

Since the coils l4, l5 and 16 each have a smaller number of turns thanthe coils 42a, lla-and 40a, respectively coupled thereto, there is anupwards transformation of voltage therebetween. The voltagetransformations, down at the antenna and up at the receiver at theopposite ends of the link circuit results in good energy transfer andyet permit the transmission line to operate at a lower voltage therebyreducing the effect of the shunt and stray capacity of the line.Furthermore, this transformation produces a better impedance matchbetween the high impedance tuned antenna circuit and the untunedtransmission line, and between the line and the high impedance tunedinput circuit of the receiver. In the specific embodiment of theinvention shown, the loop antenna 61 is arranged to operate on the3l-meter, the 25-meter, and the iii-meter.

bands, these being the bands controlled by the switch bars 40, 4| and42, respectively. It will, however, be understood that any desirednumber of condensers may be provided so as to be brought into parallelrelation with the condenser Ill and the windings I4, 15 and 16 should belikewise increased in number. 7

Thus, I may provide, instead of the switch 1|, a five-position switch,and provide two condensers in addition to 12 and I3, arranged to beconnected in parallel with the condenser 10 by the five-position switch.In addition, twowindings in series with the windings I4, and 19, wouldbe provided in the same relation with the coils associated with the bars39 and 43 as the cells l4, l5 and I6 bear to the coils associated withthe bars 42, 4|, and 40, respectively.

The switch H is mounted on the housing 69 and is provided with aprojecting button ll (Fig. 6). It will, of course, be understood thatsuitable indicia (not shown) is associated with the button 11 so as toindicate the particular short wave The edge of the wheel 19 projects outof the housing 99 so that it can be actuated manually to provide aslight adjustment of the condenser 10. This slight adjustment correctsfor variable capacity effects introduced by variable mounting of theloop relative to conductors such as the body of a steel car.

The connection of the loop 61 and the coil 18 of the link circuit to thereceiver will now be described in detail. The connections comprise acommon conductor 82- which is a shield. This shield extends to the plug84 where it is connected, as previously indicated, to one end of theloading coil 63 and to the fifth prong of the plug.

Within this shield is a conductor 0| which is connected to the other endof the coil 19. This conductor is connected to the fourth prong of theplug 84. The shield 82 and conductor 9| form a coaxial line. Of coursetwo separate wires may be used, if desired, but the shielded lineprovides one of the simplest means of achieving the desiredcharacteristics of the transmission line, namely, low signal radiationloss and stray radiation pick up, and relatively low shunt capacity. Ofimportance, for obtaining suitable signal pickup in a shieldedstructure, is the tuned loop antenna winding 81 which is coupled throughan untuned link circuit to the input circuit of a receiver tuned to thesame frequency as is the loop antenna.

The composite link circuit includes the first coil 18 on one end of theconductors 82, ill and on the other end the serially connected coils 14,I5 and 18 which, for purposes of analysis, may be grouped and consideredas a second coil serially connected with said first coil 18 through theelongated conductors 92, 9| comprising, preferably,

the co-axial cable, as shown in Figure 6.

Coil 18 is mounted near to and coupled to antenna 91 directly throughtransformer action, the winding of antenna 91 serving as one element ofthe transformer. and coil" serving as the other element of thetransformer. This type of coupling is preferred, inasmuch as a minimumnumber of circuit elements is necessary and efficiency of energyconversion is high.

Of importance in short-wave reception, is that tuning of the antenna 91and tuning of the input circuit of the receiver results in highselectivity andhigh image ratio. This is especially desirable at highfrequencies.

Furthermore, the particular arrangement of the link circuit with thetuned loop antenna and tuned receiver input circuit results in adecrease in both'the inductance at the loop antenna and at the inputcircuit of the receiver, in accordance with the principles set forth in"Radio Engineer's Hand Book, by Frederick E. Terman, 1943, published byMcGraw-Hill Book Company.

Furthermore, inasmuch as the over-all co-eiilcient of coupling betweenthe tuned loop antenna 91 and the tuned input circuit of the receiver isquite small, the tuned loop antenna 81 is coupled in small degree to thetuned input'circuit, as is evidenced by the constructions shown in Figs.6. 8 and 11. It is remembered that the co-efiicient of coupling betweentwo circuits is a ratio and is defined as the ratio of the mutualinductance actually present between two windings to the maximum possiblevalue that can occur. In accordance with this accepted definition of theco-eiiicient of coupling. the magnitude of the coupling between loopantenna 81 and adjacent link circuit coil 13 in Figs. 6 and 11 is in therange of .15 to .25.

The co-efiicient of coupling between the tuned input circuit of thereceiver and the adjacent link circuit coil, comprising, in fact, threecoils I4, 15 and 16, has as its maximum possible theoretical magnitudeone-third or .33, inasmuch as the flux from only one of such coils 14,13 and I6 threads the magnetically coupled input circuit of thereceiver. As shown by Fig. 8, the secondary coils 43A, HA, and 42A are.respectively, close to their associated iron cores, and primary coils16, I and I4 are spaced a substantial distance from the correspondingsecondary coils and cores. Therefore, the co-efflcient of couplingbetween each of the coils 16, I5 and I4 and its associated secondarycoil is substantially less than unity, with the result that theco-eiilcient of coupling between the link circuit coil comprisingserially connected coils I4, 15 and I6 is substantially less than thepossible theoretical maximum magnitude of .33.

In accordance with a commonly accepted deiinition of loose" and "tightcoupling, as set forth in the above-mentioned "Radio Engineer's HandBook, these recited magnitudes of the various coupling co-eiiicients of.15 to .25 and .33 neither correspond to tight" coupling nor to "loose"coupling, inasmuch as such publication states that closely coupled coilsusually have a coupling co-eflicient of .5 or greater, and looselycoupled coils have a coupling co-eiiicient of .01 or less. Thus, thesetwo magnitudes of .15 to .25 and .33 fall within a range which, forpurposes of this specification, corresponds to a state of mediumcoupling.

The short-wave loop antenna shown herein is thus not tightly coupled tothe input circuit of the receiver upon consideration that the overallcoupling is the product of the individual coupling co-eiiicients andwhich has a maximum product of .25 .33 or .0825. Of course, this actualmagnitude of .0825 for the over-all coupling co-efficient is the maximumtheoretical magnitude and, for the reasons explained, is smaller inactual physical receivers embodying apparatus having the precisearrangement of elements shown herein.

This small degree of coupling, which gives emcient energy transferconsistent with high selectivity and good image ratio, is desirable notonly for the reasons stated above including making it possible to tunethe loop 31 substantially independently of the receiver but also becauseit makes possible the use of a critical amount of coupling which bydefinition is the condition for maximum energy transfer. In accordancewith the present invention, I also provide a fish-pole or extensible rodantenna 33 which is normally housed in telescoped and unerectedposition, as shown in Fig. 3, the fish-pole antenna being then locatedin the rear of the housing. To render the fish-pole antenna operative,the rear door of the receiver housing is opened and the telescopedfish-pole antenna 93 is swung into vertical position, that is, thepositionin which it is shown in dottedlinesinl'ig.3.Ibrtbispurpocethelowasvaees ermost section of the fish-pole antenna 33is rigidly arried on a lever 34.

The lever 34 is pivotally mounted on a bracket 35 secured to one side ofthe case 23 of the re ceiver. When the fish-pole antenna 33 is erected,its lowermost section is brought into registry with two semi-circularopenings 30 in the upper wall of the case 20 and on the upper edge ofthe rear door thereof so that this door may now be closed, leaving thefish-pole antenna projecting upwardly from the case in the verticaldirection. It will, of course, be understood that the fish-pole antennamay be pulled out or extended in normal manner, illustrated in Fig. 9,with respect to a modified arrangement of fish-pole antenna.

Referring to Figs. 4 and 5, it will be readily understood that when thelever 04 is swung by the movement of the fish-pole antenna 33 intoerected position, one end of the lever 34 engages a projection 31 andmoves it upwardly, thus displacing contacts 33. II and III. upwardly.These contacts are elements of the three switches 33, 93 and Hill shownin Fig. 8. These switches are shown in Fig. 8 in the condition in whichthey are after the fish-pole antenna has been erected. It will beunderstood that when the fish-pole antenna is again unerected or turnedinto horizontal position, the switches I3 and II assume their differentpositions and the switch I 03 becomes closed.

In the embodiment of the invention shown in Figs. 9 and 10, a differentfish-pole antenna I23 is employed. This fish-pole antenna has a lowersection I2I which is fixedly mounted within the case 23 of the receiver.As shown in Figs. 9 and 10, the fish-pole antenna comprises a pluralityof sections which can be telescoped together. When fully telescoped, theknob I22 of the fishpole antenna projects from the upper side of thecase 23 as shown in dotted lines in Fig. 9. The fish-pole antenna may,of course, be extended fully or to a desirable degree by merely graspingthe knob I22 and pulling it upwardly.

The innermost section of the fish-pole antenna consists of a rod I23which is somewhat longer than the other sections of the fish-poleantenna. Consequently. when the fish-pole antenna is fully telescopedback into the case 23, the rod I23 projects beyond and below thelowermost section III. In this embodiment of the invention the switchelements 93, l0 and I" are adapted to be actuated by the movement of aprojection 31, this projection having a portion extending below thefish-pole antenna so as to be actuated by the rod I23. The projection31' is biased upwardly by suitable springs.

It will readily be understood that when the knob I22 is moved upwardlyfrom its normal position and when the knob I22 is returned to its normalposition, the same switching operation eifected by the erection andreclining or the fishpole antenna 93 will take place.

The loop antenna shown in Fig. 11 differs from the loop antenna I!primarily in that it consists of two turns I 24 of relatively stin wire.This wire is sufficiently strong so that it does not need to be enclosedin a dielectric tube as shown in the previously described embodiment.

The two turns I24 are supported where they enter the housing 33 by meansof two bushings I25 of suitable dielectric material. The two loops I24are further secured together preferably at a position remote from thehousing 33 by means oi a suitable block or spacer I2! of insulatingmaterial. The remainder of the elements associated with the loops I24may be precisely the same as in the previously described embodiment.

The operation is as follows: To prepare the receiver for batteryoperation, the four-pole switch 48 is thrown to the right, as viewed inFig. 8, and the double-pole single-throw switch 3| is closed, supplyingelectrical ener y to the tubes. On the other hand, if it is desired tooperate from power lines with A. C. or D. C. current, the plug 48 isplugged into a suitable outlet, the switch 48 is thrown to the left, asviewed in Fig. 8, and the switch 8| is used as an on and off" switch asit was when the receiver was battery operated.

For operation in the broadcastband, the antenna employed is selected inaccordance with the location. At the beach .or at a football game, it ispreferred to employ the fish-pole antenna 88 for this puropse, whereason a train or in a metal airplane, or indeed in any partially shieldedstructure or in any location where there is a large amount of man-madestatic, better results will be obtained with the loop 58.

Operation with the loop 56 will first be described. The loop 56,together with the loop 81, is mounted by means of the section cups 58 ata suitable location on a train window as shown in Fig. 1. Considerableimprovement in reception can usually be obtained by slight changes ofthe mounting position on the window and changes of orientation of theloop relative to the window.

The broadcast bar 88 is pushed inwardly and tuning is effected by meansof control 25, the

' volume being controlled by the button 28 which actuates the switch 8|.The tuning is indicated on the scale and indicia 85, this being thebroad cast scale.

Reception is improved by orientating the loop 55 relative to the plates58 whereby the loop is brought into the best plane for reception.Reception may be improved further by operating the switch 65 into thebest of its three positions.

Since the fish-pole antenna 83 is in its unerected position, theswitches 88 and 88 are in their other positions from those shown in Fig.8, switch I being closed.

Consequently, conductor 6| is connected directly to the control grid ofthe RF amplifier tube 50. The loop is tuned by the condenser 28 of thegang of condensers, the other side of the condenser 28 being connectedthrough loadin coil 83 to conductor 82.

Since the broadcast bar 38 has been actuated, its upper portion in Fig.8 is displaced upwardly and its lower portion in that figure isdisplaced downwardly. As a result of the upward displacement of the bar38, the high side of the secondary of the radio frequency transformerI0| is connected through condenser I02 to a grid of the mixer tube 5|.Unless the bar 38 is pushed inwardly, this connection is not made andconsequently no broadcast signal can pass from the radio frequency tube500 to the mixer tube 5|.

It may be noted that the condenser I02 is relatively large being, for,example, a .02 microfaraci condenser. On the other hand, the condenserI08 which connects the high side of the secondary of the transformer |0|to the condenser I02 is very small, having a capacity of around 15micro-microfarads. Thus at broadcast frequencies the condenser I03 isnot large enough to couple the secondary of transformer |0I to the mixertube 5|. Condenser I03 is used in short wave reception as will bedescribed. The actuation of the bar 38 shorts the condenser I08.

The actuation of the bar 88 tunes the oscillator tube 55 to anappropriate frequency band. The

vquency tube 50.

grid of this tube is connected through condenser I04, contacts I05 andI05 to the tank circuit I01, the other side of which is connected toradio frequency ground. Radio frequency ground is determined bycondenser I08 which may suitably be a .1 microfarad condenser. Thecathode of the tube 55 is connected thereto through condenser I08 whichmay suitably be a .07 microfarad condenser. The plate of the tube 55 isconnected through condenser H0 and contacts .III and H2 to a coil IIIcoupled to the tank circuit I01.

The same circuits are established when an ouii'idggr aerial is employedwith the aid of the co Employing the fish-pole antenna 88, the erectionof the fish-pole or its extension in the case of a fish-pole of thesecond described variety. moves the switches 88, 88 and 00 into thepositions in which they are shown in Fig. 8. The circuit of loop 58 isnow broken and signal passes from the flshpole antenna 88 through switch88, through contacts on the actuated bar 88 up to the tap on coil 4 toradio frequency ground.

Condenser H5 is a trimmer to compensate for variations in fish-polecircuit capacities. The signal energizes the circuit including coil 4and tuning condenser 28, the high side of which circuit is connected toa grid of the radio fre- The oscillator circuit is as previouslydescribed.

The fish-pole 88 can also be employed in the case ofall the short wavebands. In this connection it is pointed out that when operating on anyof the short wave bands, the broadcast bar 88 is in its outer position,so that no broadcast signal from the loop 58 can pass to the mixer ashas previously been described. At short wave frequencies the loop 58 issubstantially shorted so that substantially no short wave signal passesfrom tube 50 to tube 5| even though they are (iglalpled at thesefrequencies through condenser If the button 43 is actuated, thefish-pole signal passes to coil 48a, the low side of which is connectedto radio frequency ground. The high side of the coil 43a is connectedthrough the unactuated bar 88 and through coupling condenser I02 to agrid of the mixer tube 5|. At the same time the high side of the coil43a is connected through the relatively small condenser I08 to the highside of the tank circuit including'the secondary of the transformer IOIand the tuning condenser 28. The condenser 28 tunes the signal inputcircuit of tube 5| in coordination with the tuning of the oscillatorcircuit. The coil 43a thus forms a part of a circuit tuned to the signalfrequency.

The actuation of the bar 48 (lower portion in Fig. 8) connects thecircuit of the grid of oscillator tube 55 to-the upper end of coil 48b,the lower end of which (actually a tap) is connected to radio frequencyground.

At the same time the plateof the oscillator tube 55 is connected throughcondenser H0 and the bar 43 to the coil 480 coupled with coil 48!), theother end of the coil 48c being connected to radio frequency ground(actually the same tap).

The grid of the oscillator tube 55 is connected through condenser I04and contacts I05 and 8 on the unactuated bar 88 to a condenser Ill. Thecondenser III is connected to radio frequency ground by a condenser II 8and it is also connected by contacts III and I on the unactuated bar 38to the tank circuit I01. This permits the use of condenser 30 as a bandspread tuner. Since this condenser is in series with the small condenserII! and is shunted by fixed condenser II8, the effect in change ofcapacity when condenser 30 is varied is, therefore, very small. Theoscillator frequency is thus tuned by the variable condenser 30 to givean appropriate oscillator frequency for this band.

Similar results can be obtained with the bars 42, ll and 40. theassociated coils being indicated 42a, 42b, and "c, etc.

The bar 89 controls an oscillator circuit in precisely the same way asthe bars 40 to 03, coils corresponding to 4012, 40c being designated 30band 39c, respectively. The fish-pole signal, however. goes through thecoil 39a to radio frequency ground. This coil is inductively coupled toa winding 38d, thus decreasing the coupling of the fish-pole-to theinput circuit. The winding 39d is connected through the two uppermostcontacts on bar 38 (Fig. {3) through condenser I 02 to the grid of themixer tube SI and throu h condenser I03, to the tank circuit includingthe secondary of transformer I M and the tuning condenser 29.

When the button 38 is not in actua ed condition and when the fish-poleantenna 83 is in its unerected osition or the corresponding fish-poleantenna I20 is in fully telescoped condi ion. both the loop 56 and thefish-pole are rendered inoperative. In the first case. the hi h side ofthe secondary of the transformer IOI is effectively disconnected and inthe second case the switch 99 is opened.

The receiver is now in condition for o eration by the loop 61 (or the euival nt 1000 I24). It is to be noted that the switch I M is closed whenthe fish-pole is stowed away. This switch may be omitted if desiredsince when the fish-pole antenna is in operation. the two locus 50 and61 are stowed away in the back of the case 20. At the hi h frequenciesfor which the loop 61 is suited, this loop is substantially shielded bythe other nearby conductors in the case and is not in the leasteffective. However. in some cases it is preferred to use the switch I00and if it is used. it must be closed when short wave loop reception isdesired.

The loop 81 being mounted on w ndow 60 of a railroad car. for exam le.it is orientated manually to give best reception and the button I0, I or42 is pushed in accordance with the band which it is desired to receive.

The switch II is moved into the corres onding position to select thesame band. this switch being located on the housing 69 of the loop 61 ashas been previously described. 1

The receiver is. of course. turned on by the switch 3| on the volumecontrol 20 and tuning is effected by means of the button 25 to bring inthe desired station. Control wheel I9 may then be adiusted to tune theloop 01 accurately within the selected band to the station manuallyselected by button 25. Slight correction for variation of capacity ofthe loop 01 by reason of varying position on the window 00 is alsoreadily taken care of by actuating the control wheel 19 of the condenserI0.

The signal from the loop 01 is conveyed through the link circuit whichincludes the coil I0, the leads 02 and 8| and the coils I4, I! and IS.The signal is transferred from the appropriate one of these coils to thecoil "a, "a. or a, depending upon which of the three buttons 42, 4| or40 is in the actuated position.

As has previously been explained, one end of each of the coils 42a, Ilaand 40a is connected to radio frequency ground and the high sides ofthese coils are connected, when their respective buttons 42, H and 40are pushed, to the grid of the mixer tube BI and to the tuning condenser29 in the manner previously described in connection with short waveoperation with the fishpole antenna.

Although the invention has been described in connection with specificdetails of preferred embodiments thereof, it must be understood thatsuch details are not intended to be limitative of the invention exceptin so far as set forth in the accompanying claims.

Having thus described my invention, I declare that what I claim is:

1. In combination, a radio receiver, said receiver having an inputcircuit, a loop antenna winding spaced a substantial distance from saidinput circuit, a low impedance untuned hnk circuit extending betweensaid input circuit and said antenna winding and arranged to transferradio frequency energy therebetween, said link circuit including a coilhaving less turns than said antenna winding, means mounting said antennawinding and coil in close proximity to one another such that saidantenna winding and coil comprise elements of a transformer, and meansfor tuning said input circuit to a frequency equal to the frequency atwhich said antenna. winding is tuned whereby radio energy is efficientlytransferred between said antenna winding and link circuit and variationsof stray capacity of said link circuit produce no substantial effect ontransfer of such radio energy.

2. In combination, a radio receiver, said receiver having a plurality ofinput circuits tunable to the frequency of signals in any one of aplurality of bands in a relatively large frequency spectrum, means fortuning said input circuits, each of said input circuits including acoil, a loop antenna arranged to be mounted remotely from said receiver,means proximate to said loop for tuning it to a predetermined resonantfrequency corresponding to a frequency in any one of said plurality ofbands, a low impedance untuned link circuit arranged to pass signals inall of said bands and coupling said loop antenna to said coil of each ofsaid input circuits, and means for selectively connecting one of saidtunable input circuits to said receiver for the transfer of signals fromsaid link circuit to said receiver.

3. In combination, a portable radio receiver unit having an inputcircuit, a coil connected in said input circuit for the transfer ofenergy to said unit, means for tuning said coil to a frequency desirablefor operation of said radio unit, a short wave loop antenna arranged tobe mounted remotely relative to said unit, means proximate to said loopfor tuning it to a predetermined resonant frequency equal to the firstmentioned frequency, an untuned link circuit coupling said loop antennato said coil in,said input circuit, said link circuit comprising: atwo-conductor cable extending from said loop antenna to said unit andhaving its conductors connected to opposite terminals of a first coilcoupled to said loop antenna for voltage stepdown from the loop to saidfirst coil and having its conductors connected to a second coil coupledto said coil in the input circuit, for the transfer of signals receivedin said loop antenna to said input circuit.

4. In combination, a radio receiving unit, a plurality of input circuitstunable to the frequency of signals in any one of a plurality of bands,each of said input circuits including a coil, means for tuning said coilto a frequency desirable for operation of said radio unit, a loopantenna arranged to be mounted remotely from said unit, means proximateto said loop for tuning it to a predetermined resonant frequency equalto the first mentioned frequency and corresponding to a frequency in anyone of said plurality of bands, 3, low impedance untuned link circuitcoupling said loop antenna to said coil of each of said input circuits,said link circuit comprising: a twoconductor cable extending from saidloop antenna to said unit and having its conductors connected toopposite terminals of a first coil near said loop antenna for voltagestepdown between said loop antenna and said first coil and having itsterminals connected to opposite terminals of a second coil coupled tosaid 0011 in each of said input circuits, for the transfer of energyfrom said loop antenna to said input circuit, and means for selectivelyconnecting one of said tunable input circuits to said unit for thetransfer of signals from said loop over said link circuit to said unit.

5. In combination, a radio receiver having an input circuit, a shortwave loop antenna arranged to be mounted remotely from said unit, a basestructure carrying said loop, variable capacitance means proximate tosaid loop for tuning it to any selected one of a group of predeterminedresonant frequencies, an untuned coil mounted on said base and coupledto said loop for substantial voltage stepdown from said loop to saiduntuned coil, means comprising a low impedance network for transferringa voltage induced in said coil to the input circuit of said receiver,and means for tuning said input circuit to the said having such a numberof turns so that it serves to produce such substantial voltage stepdownand serves to match the impedance of the resulting tuned loop antennawith the impedance of such transferring means.

6. In combination, a receiver having an input circuit, a short wave loopantenna comprising a loop, a base structure carrying said loop, mountingmeans for said base whereby the loop may be located in desiredpositions, hinge means connecting said base to said mounting meanswhereby said loop may be oriented for best reception, variablecapacitance means proximate to said loop whereby it may be tuned to apredetermined resonant frequency, a coil coupled to'said loop andmounted on said base, means for transferring a voltage induced in saidcoil from said loop to the input circuit of said receiver, and means fortuning said input circuit'to the same frequency as said predeterminedresonant frequency.

7. In combination, a radio receiver having an input circuit, a shortwave antenna comprising a loop, a base structure arranged to be placedremotely from said receiver and carrying said loop, a plurality ofcapacitors carried by said base, switching means for cutting individualcapacitors into circuit with said loop whereby the same is tuned to anyone of a plurality of predetermined resonant frequencies, a lowimpedance coil coupled to said loop for substantial voltage stepdownfrom said loop to said coil, said coil being mounted on said base, meansfor transferring a voltage induced in said cell from said loop to theinput circuit of said receiver, and

means for tuning said input circuit to the same frequency. as saidpredetermined frequencies.

8. In combination, a portable radio receiver unit having an inputcircuit, means for tuning said input circuit to a frequency desirablefor operation of said radio unit, a short wave loop antenna arranged tobe mounted remotely relative to said unit, variable capacitance meansarranged to tune said loop to a predetermined resonant frequency in aband of frequencies, and an untuned low impedance link circuit coupledto said-loop and coupled to said input circuit of the unit for thetransfer of radio ener y selectively received in said loop to said unit.

, 9. In combination, a radio receiver-having an input circuit, :meansfor tuning said input circuit to a frequency desirable for operation ofsaid receiver, a loop antenna arranged to be mounted in remote relationthereto, an untuned low impedance link circuit coupled to said antennafor substantial voltage stepdown from said loop to said link circuit,said link circuit being coupled to said input circuit and extendingbetween said loop and radio receiver to communicate signals from saidantenna to said receiver, and means proximate to said loop antenna forchanging its resonant frequency to the first mentioned frequency.

10. In combination, a radio receiver having an input circuit, a pair ofloop antennas, mount- .ing means -whereby said antennas may be mountedin alignment with a suitable dielectric surface, means pivotallyconnecting. said loop antennas to said mounting means whereby said loopantennas may be oriented in the most advantageous direction for signalreception, tuning means proximate .to one of said loop antennas wherebythe same is adapted for the reception of a plurality of bands, a firstcoil coupled to said one loop antenna for substantial voltage stepdownfrom said last one loop antenna to said first coil, a second coilcoupled to said input circuit, a pair of conductors extending betweenand connecting said first and second coils, said first coil and secondcoil and conductors comprising a link circuit, conductors connecting theother loop antenna to the input circuit of the receiver, cable meansincluding all of said conductors, and switching means on the receiverfor rendering each of said loop antennas alternatively effective totransfer signals to said receiver.

11. In combination, a radio receiver having an input circuit, a pair ofloop antennas, mounting means whereby said antennas may be mounted inalignment with a suitable dielectric surface, means pivotally connectingsaid loop antennas to said mounting means whereby said loop antennas maybe oriented in the most advantageous direction for signal reception,tuning means proximate to one of said loop antennas whereby the same isadapted for the reception of a plurality of broadcast bands, a firstcoil coupled to said one loop antenna for substantial voltage stepdownfrom said one antenna to said coiL-a' second coil coupled to said inputcircuit, a pair of conductors extending between and connecting saidfirst and second coils in a series circuit, said series circuitcomprising an untuned low impedance link circuit, conductors between theother loop antenna and input circuit of the receiver, cable meansincluding said first and last mentioned conductors, switching means onthe receiver for rendering each of said loop antennas alternativelyeffective to transfer signal energy to said receiver, said switchingmeans including and selecting means for adapting the receiver or thereception of signals in any of a plurality of said bands.

12. In combination, a radio receiver having an input circuit and ahousing, a pair of loop antennas, mounting means whereby said antennasmay be mounted in alignment with a suitable dielectric surface, meanspivotally connecting said loop antennas to said moimting means wherebysaid loop antennas may be oriented in the most advantageous direction I1' signal reception, tuning means proximate to one of said loop antennasfor tuning it at a predetermined resonant frequency for the reception ofsignals in a pluralitybf bands, a first coil coupled to said ne loopantenna for substantial voltage stepdown, a second coil coupled to saidinput circuit, conductors extending between and connecting said firstand second coils in a series circuit, said first coil, second coil andconductors forming an untuned low impedance link circuit, at least oneadditional conductor extending between and connecting the other loopantenna to the input circuit of the receiver, cable means including allof said conductors and extending from said loop antennas to thereceiver, a telescopic antenna,.said telescopic antenna being of suchsize with respect to said housing and arranged so that said antenna maybe moved from a position substantially within said housing to a positionwhere said antenna extends substantially entirely outside of saidhousing, switching means for alternatively connecting said other loopantenna and said telescopic antenna to said input circuit, an operatingmember for said switching means positioned in the path of movement ofsaid telescopic antenna such that movement of said telescopic antennabetween said position substantially within said housing and said podtionsubstantially outside of said housing results in alternativelyconnecting said other loop and said telescopic antenna to said inputcircuit, and switching means on the receiver for rendering each of saidloop antennas alternatively effective to transfer signals therefrom tosaid input circuit.

13. In combination with an antenna for the reception of radiated energy,a receiver arranged to be energized by such energy and located at asubstantial distance from said antenna, a tuned input circuit for thereceiver, said antenna being tuned to the same frequency as said inputcircuit a low impedance link circuit extending between said antenna andreceiver and including means at its ends for coupling said antenna tosaid link circuit and for coupling said link circuit to said inputcircuit of the receiver, said coupling means comprising means forreducing the voltage of said energy passing from said antenna to saidlink circuit and for increasing the voltage of said energy from saidlink circuit to the input circuit of said receiver.

14. In combination, radio apparatus, a housing for the radio apparatus,said radio apparatus including metal parts, a first antenna, a secondantenna, means within said housing for movably mounting said firstantenna with respect to said housing, said first antenna being of suchsize with respect to said housing and arranged so that said firstantenna may be moved from a position substantially within said housingwherein said metal parts impair the eifectiveness of said first antennato a position substantially entirely outside of said housing whereinsaid metal parts in fiuence in small degree the effectiveness of saidfirst antenna, and switching means for rendering said first antenna andsaid second antenna alternatively effective for the passage of signalsbetween said antennas and said apparatus, said switching means includinga member arranged to move with said first antenna during at least aportion of the movement of said first antenna between said positionwithin said housing and said position outside of said housing, saidmemher being arranged to disconnect said second antenna from saidapparatus and to'connect said first antenna to said apparatus inresponse to movement of said first antenna to said outside position, theresulting connections being reversed upon movement oi said first antennato said position within said housing.

15. In combination, radio apparatus including an energy transferringcircuit a houisng for said apparatus, said radio apparatus includingmetal parts, an antenna movable from a position within said housingwherein said metal parts impair the effectiveness of said antenna to aposition substantially outside of said housing wherein said metal partsinfluence in small degree the eiiectiveness of said antenna, and meansincluding an operating member positioned in the path of movement of saidantenna operated in response to movement of said antenna from saidposition within said housing to a position outside of said housing forelectrically connecting said antenna to said circuit for the transfer ofradio energy between said radio apparatus and antenna.

16. In combination, a radio apparatus, a housing for said radioapparatus, said radio apparatus including metal parts, a first antenna,a second antenna. means for movably mounting said first antenna withrespect to said housing,

40 said first antenna being of such size with respect to said housingand arranged so that said first antenna may be moved from a firstposition substantially within said housing wherein said metal partsimpair the efiectiveness of said first antenna to a second positionsubstantially entirely outside of said housing wherein said metal partsinfluence in small degree the eflectiveness of said first antenna, andmeans including an operating member positioned in the path of movementof said first antenna operated in response to movement of said firstantenna between said position within said housing to said positionsubstantially entirely outside of said housing for alternativelyconnecting electrically said antennas to said apparatus for the passageof signals therebetween. 7

17. In combination, radio apparatus including a radio energytransferring circuit, said apparatus including metal parts, a firstantenna movable from a position relatively near said apparatus whereinthe eil'ectiveness of said antenna is impaired by said metal parts to aposition more remote from said apparatus wherein said metal partsinfluence in small degree the efiectiveness of said antenna, a secondantenna, and means responsive to movement of said first antenna fromsaid position relatively near said apparatus to said more remoteposition for electrically disconnecting said second antenna from saidenergy transferring circuit and for electrically connecting said firstantenna to said energy transferring circuit for the transfer of radioenergy between said radio apparatus and first antenna, saiddisconnecting and connecting means including a member arranged to movewith said first antenna during at least a portion of the movement ofsaid first antenna between said positions, said member being arranged tomove to open a circuit between said second antenna and said energytransferring circuit in response to said move-. ment and to close acircuit between said first antenna and said energy transferring circuitin response to said movement.

18. In combination, a radio receiver having a housing, said receiverincluding metal parts, a telescopic rod antenna mounted on said receiverfor transferring signals thereto and arranged to extend substantiallywithin said housing when the antenna is telescoped wherein said metalparts impair the effectiveness of said antenna and to extendsubstantially outside of said housing when the antenna is extended inwhich position said metal parts influence in small degree theeffectiveness of said antenna, a second antenna for transferring signalsto the receiver, switching means including an operating memberpositioned in the path of telescoping movement of the first mentionedantenna operated in response to movement of said first mentioned antennafrom its telescoped position within said housing to its extendedposition outside of said housing for rendering said first mentioned andsecond antennas alternatively effective for the passage of signalsbetween said antennas and receiver.

19. In combination, a radio receiver, said receiver including metalparts, a telescopic antenna mounted on said receiver for transferringsignals thereto and arranged to be positioned in close proximity to saidreceiver when the antenna is telescoped in which position said metalparts impair the effectiveness of said antenna and to extend asubstantial distance away from the receiver when the antenna is extendedin which position said metal parts influence in small degree theeffectiveness of said antenna, a loop antenna for transferring signalsto the receiver, and switching means for rendering said first and secondantennas alternatively effective for the passage of signals between theantennas and receiver, said switching means including a member arrangedto move with said first mentioned antenna during at least a portion ofthe movement of the first mentioned antenna from its position close tosaid receiver to its position a substantial distance from said receiver,said member being arranged to move to disconnect said loop antenna fromsaid receiver and to connect said first mentioned antenna to saidreceiver in response to saidmovemen-t.

20. In combination, radio apparatus, a housing for said apparatus, saidapparatus including metal parts, an antenna, means within said housingfor movably mounting said antenna with respect to said housing, saidantenna being of such size with respect to said housing and arranged sothat said antenna may be moved from a position substantially within saidhousing wherein said metal parts impair the effectiveness. of saidantenna to a position where said antenna extends substantially entirelyoutside of said housing wherein said metal parts influence in smalldegree the effectiveness of said antenna, and means including anoperating member positioned in the path of movement of said antennaresponsive to movement of said antenna from said position substantiallywithin said housing tosaid position entirely outside of said housing foroperatively connecting electrically said antenna to said apparatus forthe passage of signals therebetween,

21. In combination, radio apparatus, a housing for said radio apparatus,said apparatus including metal parts, an antenna movable from a positionwithin said housing wherein said metal parts impair the efiectiveness'ofsaid antenna to a position outside of said housing wherein said metalparts influence in small degree the eiiectiveness of said antenna, andmeans including an operating member positioned in the path of movementof said antenna responsive to movement of said antenna from saidposition within said housing to said position outside of said housingfor electrically connecting said antenna to the apparatus for thepassage of signals therebetween.

22. In combination, radio apparatus, a housing for said apparatus, atelescopic rod antenna for the reception of signals and movable from atelescoped position within said housing in close proximity to saidapparatus to an extended position outside of said housing removed fromsaid apparatus, said apparatus having metal parts which materiallyinfluence a function of the antenna when said antenna is positionedwithin said housing and in proximity to said apparatus, and means forconnecting electrically said antenna to the apparatus for the passage ofsignals therebetween, said connecting means including a member arrangedto move with said antenna during at least a portion of the movement ofsaid antenna between its telescoped and extended positions, said memberbeing arranged to move to close a circuit between said antenna and saidapparatus in response to said movement.

23. In combination, radio apparatus normally disposed near the earthssurface, a rod antenna attached mechanically to said apparatus andmovable from a vertical position with respect to the earth's surfacewhere said antenna is highly effective to pass signals to a positionwhere said rod antenna extends substantially parallel to the earthssurface, and means for operatively connectmg electrically said antennato said apparatus for the passage of signals therebetween, saidconnecting means including a member arranged to move with said antennaduring at least a portion of the movement of said antenna from saidhorizontal position to said vertical position, said member beingarranged to move to close a circuit between said antenna and saidapparatus in response to said movement.

24. In combination, radio apparatus including a radio energytransferring circuit, a first antenna movable with respect to saidapparatus, a second antenna, and switching means for alternatelyconnecting said first antenna and second antenna electrically with saidradio energy transferring circuit for the alternate transfer of radioenergy between said antennas and said apparatus, said switching meansincluding a member arranged to move with said first antenna during atleast a portion of the movement of said first antenna with respect tosaid apparatus, said member being arranged to move to connect saidcircuit to one of said antenna and disconnect said circuit from theother antenna in response to said movement.

25. In combination, means for receiving radio frequency energy, saidmeans having a high impedance input circuit, a loop antenna windingspaced a substantial distance from said input circuit, a low impedanceuntuned link circuit extending between said input circuit and antennawinding and arranged to transfer radio frequency energy therebetween,said link circuit including a coil, means mounting said antenna windingand link circuit coil in close proximity to each other such that saidantenna winding and link circuit coil comprise elements of atransformer, means for tuning said antenna winding to a frequency ofsignals desirable for operation of said radio receiving means, means fortuning said input circuit to the same frequency at which said antennawinding is tuned, and means for matching the impedance of the resultingtuned antenna winding to the low impedance of said link circuit, andmeans for matching the high impedance of said input circuit in saidradio receiving means to the low impedance of said link circuit wherebyradio energy is efficiently transferred between said antenna winding andlink circuit and input circuit and variations of stray capacity of suchlink circuit produce no substantial effect on the transfer of such radioenergy.

26. In combination, a radio receiver having an input circuit, a pair ofloop antennas for the reception of radio signals, said antennas beingarranged to be mounted remotely relative to the receiver, tuning meansproximate to one of said antennas for tuning it to a predeterminedresonant frequency, means for tuning said input circuit to a frequencyequal to said predetermined frequency, means including conductors forcoupling said one antenna to the input circuit of said receiver, meansincluding at least one other conductor for coupling the other antenna tothe input circuit of said receiver, flexible cable means including saidconductors extending between said antennas and receiver, switching meanson the receiver for rendering alternatively effective said one and theother antenna to transfer signals therefrom to said input circuit, saidswitching means including band selecting means for adapting the receiverfor the reception of signals in any of a plurality of broadcast bands.

27. In combination, means for translating radio frequency energy, saidmeans having an energy transferring circuit, a loop antenna spaced 9,substantial distance from said energy transferring circuit, means fortuning said antenna to a frequency desirable for the transmission ofenergy to said translating means, a low impedance untuned link circuitextending between said energy transferring circuit and said antenna andarranged to transfer radio frequency energy therebetween, means fortuning said transferring circuit to said desirable frequency, wherebyradio energy is efficiently transferred between said antenna and linkcircuit and variations of stray capacity of said link circuit produce nosubstantial effect on transfer of such radio energy, a. low capacityantenna arranged to be connected to said energy transferring circuit,and switching means for alternatively connecting said antennas to saidenergy transferring circuit for the transfer of energy therebetween.

28. In combination, means for translating radio frequency energy, saidmeans having an energy transferring circuit, a loop antenna spaced asubstantial distance from said energy transferring circuit, meansproximate to said antenna for tuning it to predetermined frequencies, alow impedance untuned link circuit extending between said energytransferring circuit and said antenna and arranged to transfer radiofrequency energy therebetween, means for tuning said transferringcircuit to frequencies equal to said predetermined frequencies, wherebyradio energy is effectively transferred between said antenna and linkcircuit and variations of stray capacity of said link circuit produce nosubstantial effect on transfer of such radio energy, a movable lowcapacity antenna arranged to be connected to said energy transferringcircuit, and means responsive to movement of said last antenna foralternatively connecting said antennas to said energy transferringcircuit for the transfer of energy therebetween.

29. In combination, a radio receiver having an input circuit, a pair ofantennas operable for the reception of radio signals in differentfrequency bands and being arranged to be mounted remotely relative tothe receiver, means proximate to one of said antennas for tuning it topredetermined frequencies, means for tuning said input circuit tofrequencies equal to said predetermined frequencies, means for couplingsaid antennas to the input circuit for the transfer of radio frequencyenergy in diflerent frequency bands to said input circuit, and means onthe receiver for rendering each of said antennas alternatively effectiveto transfer radio frequency energy in different frequency bands to saidreceiver.

30. In combination, a radio receiver having an input circuit, a firstand a second antenna operable for the reception of signals in differentfrequency bands, means proximate to said first antenna for tuning saidfirst antenna to predetermined frequencies, said input circuit includinga plurality of tuned circuits tunable to frequencies equal to saidpredetermined frequencies and arranged to be selectively coupled to saidfirst antenna for the selective reception of signals in a plurality offrequency bands, switching means for selectively coupling one of saidtuned circuits to said first antenna, means for coupling said secondantenna to the input circuit of the receiver, and means responsive tooperation of said switching means for uncoupling said first antenna fromsaid input circuit.

31. In combination, a radio receiver having an input circuit, a firstantenna and a second antenna arranged for the reception of radio signalsin diflerent frequency bands, means for coupling said first antenna tosaid input circuit for the transfer of radio energy therebetween, meansfor coupling said second antenna to said input circuit for the transferof energy therebetween, said last mentioned means including one of aplurality of tuned circuits tuned to predetermined frequencies for theselective transfer of signals between said second antenna and inputcircuit in any one of a plurality of frequency bands, means for tuningsaid second antenna to frequencies equal to said predeterminedfrequencies, means for selectively connecting one of said plurality oftuned circuits in operative relationship for .the selective transfer ofsignals between said second antenna and input circuit, and meansresponsive to actuation of said connecting means for uncoupling saidfirst antenna from said input circuit.

32. In combination, an antenna, means proximate to said antenna fortuning the same to a single frequency within a range of frequencies,radio receiving apparatus, an input ,circuit for said radio receivingapparatus located remotely relative to said antenna, means for tuningsaid input circuit to a single frequency equal to the .first mentionedfrequency, and a low impedance circuit coupling the resulting tunedantenna to the resulting tuned input circuit, the overall cou plingbetween the antenna and input circuit being of small degree such thatefilcient energy transfer consistent with high selectivity and imageratio results.

33. In combination, a radio receiver, said receiver having a pluralityof input circuits each tunable to the frequency of signals in adifferent range, means for connecting any selected one of said tunableinput circuits to said receiver, means for tuning the selected circuitto any desired signal frequency within its range, a loop antennaarranged to be mounted remotely from said receiver, antenna tuning meansproximate to the loop comprising discontinuous means for tuning the loopto any selected one of a plurality of frequencies each in a differentone of said ranges and continuous means for tuning the loop to anysignal frequency within the range for which the discontinuous means hasbeen set, and means for coupling said antenna to the selected inputcircuit, said coupling means comprising a line having a coil at one endcoupled to said loop antenna for substantial voltage stepdown fromantenna to coil, means to match the impedance of said loop antenna tothe impedance of the line, and means to match the line impedance to theimpedance of the selected input circuit, said coupling means having alow characteristic impedance, a low shunt capacity, and providing asmall degree of coupling between said antenna and input circuit.

34. In combination, radio receiving apparatus having an input circuit,means for adjustably tuning said input circuit, a loop antenna, meansproximate to said antenna for adjustably tuning said antenna to afrequency corresponding to the frequency to which the input circuit istuned, means for coupling said antenna to said input circuit, saidcoupling means comprising a.long flexible line having a coil at oneend-coupled to said loop and arranged for substantial voltage stepdownfrom said loop to said coil, the overall coupling between said loop andsaid input circuit being of small degree, and means for quicklyattachably and detachably supporting said antenna at a point removedfrom said receiving apparatus.

35. In combination, a radio receiver having an input circuit, means foradjustably tuning said tuned, and means for coupling said antenna to theselected input circuit, said coupling means comprising a line having acoil at one end coupled to said loop antenna for substantial voltagestepdown from antenna -to coil, said coupling means having a lowcharacteristic impedance, a low shunt capacity, and a low overallcoemcient of coupling.

' 37. In combination, a radio receiver, said receiver having a pluralityof input circuits tunable to the frequency of signals in any one of apin-- of frequencies each in a different one of said input circuit to afrequency desirable for operation of said receiver, a loop antennaarranged to be mounted in remote relation thereto, a line having a lowcharacteristic impedance and a low shunt capacity, means for coupling insmall degree said antenna to said line for substantial voltage stepdownfrom said antenna to said line, and means for coupling in small degreesaid line to said input circuit, said line extending between saidantenna and input circuit to communicate signals from said antenna tosaid input circuit, and means proximate to said loop antenna for tuningit to the first mentioned frequency.

36. In combination, a radio receiver, said receiver having a pluralityof input circuits tunableto the frequency of signals in any one of a.plurality of bands in a relatively large frequency spectrum, means forconnecting any selected one of said tunable circuits to said receiver,means for tuning the selected circuit to any signal frequency within theselected band, a loop antenna ceiver, antenna tuning means proximate tothis loop comprising discontinuous means for tuning the loop'to anyselected one of a plurality of frequencies each in a different one ofsaid bands, and continuous means for tuning the loop to any signalfrequency within the band corresponding to the frequency to which saidinput circuit is arranged to be mounted remotely from said rebands andcontinuous means for tuning the loop to any signal frequency within theband corresponding to the frequency to which said input circuit istuned, and means for coupling said antenna to theselected input circuit,said coupling means having a low characteristic impedance and a lowshunt capacity and a low overall coefficient of coupling and comprisinga line having a coil at one end coupled to said loop antenna, saidcoupling means being arranged to maintain the voltage thereinsubstantially lower than the voltage in either said antenna or theselected input circult, means to improve the impedance match betweensaid antenna and said line and between said line and said input circuit,and means for quickly attachably and detachably supporting said antennaat a point removed from said receiver. v

38. In combination, a. radio receiver having an input circuit, means fortuning said input circuit to any desired frequency within a range offrequencies, a first antenna, means proximate to said antenna for tuningit to the same frequency as said input circuit, said first antenna beingmovable to a position removed from said input circuit, means forcoupling said'antenna to said input circuit, said coupling means havinga low characteristic impedance and being arranged to provide overallcoupling between said antenna and said input circuit of such smalldegree that etllcient energy transfer consistent with high selectivityresults; a second antenna, and means for connecting said second antennawith said input circuit and disconnecting said coupling means therefromand alternatively for disconnecting said second antenna from said inputcircuit and connecting said coupling means thereto.

39. In combination, radio receiving apparatus having an input circuit,means for adjustably tuning said input circuit to any desired frequencywithin the short wave range, a loop antenna, means proximate to saidantenna for adjustably tuning said antenna to a frequency correspondingto said desired frequency, and long flexible means for coupling saidantenna to said input circuit, the overall coefiicient of couplingbetween said antenna and said input circuit lying in a range of mediumto loose coupling, said coupling means having a low characteristicimpedance and a low shunt capacity.

40. In combination, a radio receiver having an input circuit, means fortuning aid input circuit to any desired frequency within a range offrequencies, a first antenna, means proximate to said antenna for tuningit to the same frequency as said input circuit, said first antenna beingmovable to a position removed from said input circuit, means forcoupling said antenna to said input circuit, said coupling means havinga low characteristic impedance and being arranged to provide overallcoupling between said antenna and said input circuit of such smalldegree that efficient energy transfer consistent with high selectivityresults, a second antenna, and means responsive to movement of one ofsaid antennas with respect to said receiver for connecting said secondantenna with said input circuit and disconnecting said coupling meanstherefrom and alternatively for disconnecting said second antenna fromsaid input circuit and connecting said coupling means thereto.

41. In combination, an antenna, means proximate to said antenna foradiustably tuning the antenna to any desired frequency, radio receivingapparatus, an input circuit for said radio receiving apparatus, meansfor adjustably tuning said input circuit to a frequency equal to saiddesired frequency, and a flexible line having a low characteristicimpedance and a low shunt capacity for coupling said antenna to saidinput circuit, the overall coupling between said antenna and inputcircuit being of small degree, means for supporting said antenna andsaid line on said receiving apparatus, said line being of sufficientlength that when coupled between said antenna and input circuit, theantenna may be located at a remote point with respect to the inputcircuit, and means for quickly attachably and detachably supporting saidantenna at such a remote point.

42. In combination, means for receiving radio frequency energy, saidmeans having a high impedance input circuit, a loop antenna windingarranged to be placed a substantial distance from said energy receivingmeans. a line having a low asvaees characteristic impedance and a lowshunt capacity extending between said energy receiving means and antennawinding and arranged to transfer energy therebetwecn, said lineincluding a coil, means mounting said antenna winding and coil in closeproximity to each other such that said antenna winding and coil compriseelements of a transformer, means variable to tune said antenna windingto a frequency of signals desirable for operation of said receivingmeans, means variable to tune said energy receiving means to the samefrequency as the antenna winding is tuned, means for matching the highimpedance of the tuned antenna winding to the low impedance of saidline, and means for matching the high impedance of said energy receivingmeans to the low impedance of said line, said line being coupled to saidantenna and said receiving means in small degree.

43. In combination, a radio receiver, said receiver having a pluralityof input circuits tunable to the frequency of signals in any one of aplurality of bands in a relatively large frequency spectrum, means forconnecting any selected one of said tunable input circuits to saidreceiver, means for tuning the selected circuit to any signal frequencywithin the selected band, a loop antenna arranged to be mounted remotelyfrom said receiver, antenna tuning means proximate to the loopcomprising discontinuous means for tuning the loop to any selected oneof a plurality of frequencies each in a different one of said bands andcontinuous means for tuning the loop to any signal frequency within theband corresponding to the frequency to which said input circuit istuned, and means for coupling said antenna to the selected inputcircuit, said coupling means having a low characteristic impedance, alow shunt capacity, and a low overall coefficient of pling.

GEORGE O. BTRIK'ER.

